A medical imaging facility with a transport device able to be moved in at least one direction is already known. The medical imaging facility, for example a magnetic resonance tomography device, a computed tomography device and/or a PET device, is a highly accurate system which demands a precise detection of the position of the transport device to enable a treatment and/or an examination to be undertaken. In this procedure a patient is moved into an imaging area of the medical imaging facility, with the transport device preferably comprising a transport table which is arranged so as to be able to be moved in at least one direction. For determining the position of the movable transport device the medical imaging facility has a position detection device.
In a conventional position detection device a position of the transport device is detected by means of an encoder which is arranged in a drive unit of the transport device and/or is coupled to the latter. This method however involves a high degree of inaccuracy in the detected position of the transport device.
Another known position detection device comprises crosshairs which are moved along with a movement of the transport device. This movement of the crosshairs is detected and the position of the transport device is determined from this. The disadvantage of this method however is that, because of an elasticity and/or expansion of a material of the crosshairs, a high level of inaccuracy is contained in the detected position of the transport device.
Furthermore a position detection device with optical sensors and/or regulators for determining and/or detecting a movement and/or position of the transport device is known. However the disadvantage of this method is that these sensors and/or regulators are arranged at least partly within the imaging area and are therefore subjected to treatment and/or examination radiation. This can adversely affect both the treatment and also the position detection in an undesired manner.
Another known position detection device of a medical imaging facility also features a laser system comprising a laser source for sending out a laser signal and a detector element for receiving the laser signal. The laser signal in this case is beamed directly from the laser source onto the detector element. Usual measurement methods, such as a Time of Flight method, exhibit a high degree of inaccuracy in position determination however. In addition the laser source and/or the detector element are mostly arranged on the movable transport device and is therefore subjected to examination radiation.